/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.hbase.net;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.Socket;
import java.net.SocketAddress;
import java.net.SocketException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.UnknownHostException;
import java.net.ConnectException;
import java.nio.channels.SocketChannel;
import java.util.Map.Entry;
import java.util.*;

import javax.net.SocketFactory;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.conf.Configuration;
import org.apache.hadoop.hbase.util.ReflectionUtils;

public class NetUtils {
	private static final Log LOG = LogFactory.getLog(NetUtils.class);

	private static Map<String, String> hostToResolved = new HashMap<String, String>();

	/**
	 * Get the socket factory for the given class according to its
	 * configuration parameter
	 * <tt>hadoop.rpc.socket.factory.class.&lt;ClassName&gt;</tt>. When no
	 * such parameter exists then fall back on the default socket factory as
	 * configured by <tt>hadoop.rpc.socket.factory.class.default</tt>. If
	 * this default socket factory is not configured, then fall back on the JVM
	 * default socket factory.
	 * 
	 * @param conf the configuration
	 * @param clazz the class (usually a {@link VersionedProtocol})
	 * @return a socket factory
	 */
	public static SocketFactory getSocketFactory(Configuration conf, Class<?> clazz) {

		SocketFactory factory = null;

		String propValue = conf.get("hadoop.rpc.socket.factory.class." + clazz.getSimpleName());
		if ((propValue != null) && (propValue.length() > 0))
			factory = getSocketFactoryFromProperty(conf, propValue);

		if (factory == null)
			factory = getDefaultSocketFactory(conf);

		return factory;
	}

	/**
	 * Get the default socket factory as specified by the configuration
	 * parameter <tt>hadoop.rpc.socket.factory.default</tt>
	 * 
	 * @param conf the configuration
	 * @return the default socket factory as specified in the configuration or
	 *         the JVM default socket factory if the configuration does not
	 *         contain a default socket factory property.
	 */
	public static SocketFactory getDefaultSocketFactory(Configuration conf) {

		String propValue = conf.get("hadoop.rpc.socket.factory.class.default");
		if ((propValue == null) || (propValue.length() == 0))
			return SocketFactory.getDefault();

		return getSocketFactoryFromProperty(conf, propValue);
	}

	/**
	 * Get the socket factory corresponding to the given proxy URI. If the
	 * given proxy URI corresponds to an absence of configuration parameter,
	 * returns null. If the URI is malformed raises an exception.
	 * 
	 * @param propValue the property which is the class name of the
	 *        SocketFactory to instantiate; assumed non null and non empty.
	 * @return a socket factory as defined in the property value.
	 */
	public static SocketFactory getSocketFactoryFromProperty(Configuration conf, String propValue) {

		try {
			Class<?> theClass = conf.getClassByName(propValue);
			return (SocketFactory) ReflectionUtils.newInstance(theClass, conf);

		} catch (ClassNotFoundException cnfe) {
			throw new RuntimeException("Socket Factory class not found: " + cnfe);
		}
	}

	/**
	 * Handle the transition from pairs of attributes specifying a host and port
	 * to a single colon separated one.
	 * @param conf the configuration to check
	 * @param oldBindAddressName the old address attribute name
	 * @param oldPortName the old port attribute name
	 * @param newBindAddressName the new combined name
	 * @return the complete address from the configuration
	 */
	@Deprecated
	public static String getServerAddress(Configuration conf, String oldBindAddressName, String oldPortName,
			String newBindAddressName) {
		String oldAddr = conf.get(oldBindAddressName);
		String oldPort = conf.get(oldPortName);
		String newAddrPort = conf.get(newBindAddressName);
		if (oldAddr == null && oldPort == null) {
			return newAddrPort;
		}
		String[] newAddrPortParts = newAddrPort.split(":", 2);
		if (newAddrPortParts.length != 2) {
			throw new IllegalArgumentException("Invalid address/port: " + newAddrPort);
		}
		if (oldAddr == null) {
			oldAddr = newAddrPortParts[0];
		} else {
			LOG.warn("Configuration parameter " + oldBindAddressName + " is deprecated. Use " + newBindAddressName + " instead.");
		}
		if (oldPort == null) {
			oldPort = newAddrPortParts[1];
		} else {
			LOG.warn("Configuration parameter " + oldPortName + " is deprecated. Use " + newBindAddressName + " instead.");
		}
		return oldAddr + ":" + oldPort;
	}

	/**
	 * Adds a static resolution for host. This can be used for setting up
	 * hostnames with names that are fake to point to a well known host. For e.g.
	 * in some testcases we require to have daemons with different hostnames
	 * running on the same machine. In order to create connections to these
	 * daemons, one can set up mappings from those hostnames to "localhost".
	 * {@link NetUtils#getStaticResolution(String)} can be used to query for
	 * the actual hostname. 
	 * @param host
	 * @param resolvedName
	 */
	public static void addStaticResolution(String host, String resolvedName) {
		synchronized (hostToResolved) {
			hostToResolved.put(host, resolvedName);
		}
	}

	/**
	 * Retrieves the resolved name for the passed host. The resolved name must
	 * have been set earlier using 
	 * {@link NetUtils#addStaticResolution(String, String)}
	 * @param host
	 * @return the resolution
	 */
	public static String getStaticResolution(String host) {
		synchronized (hostToResolved) {
			return hostToResolved.get(host);
		}
	}

	/**
	 * This is used to get all the resolutions that were added using
	 * {@link NetUtils#addStaticResolution(String, String)}. The return
	 * value is a List each element of which contains an array of String 
	 * of the form String[0]=hostname, String[1]=resolved-hostname
	 * @return the list of resolutions
	 */
	public static List<String[]> getAllStaticResolutions() {
		synchronized (hostToResolved) {
			Set<Entry<String, String>> entries = hostToResolved.entrySet();
			if (entries.size() == 0) {
				return null;
			}
			List<String[]> l = new ArrayList<String[]>(entries.size());
			for (Entry<String, String> e : entries) {
				l.add(new String[] { e.getKey(), e.getValue() });
			}
			return l;
		}
	}

	/**
	 * Same as getInputStream(socket, socket.getSoTimeout()).<br><br>
	 * 
	 * From documentation for {@link #getInputStream(Socket, long)}:<br>
	 * Returns InputStream for the socket. If the socket has an associated
	 * SocketChannel then it returns a 
	 * {@link SocketInputStream} with the given timeout. If the socket does not
	 * have a channel, {@link Socket#getInputStream()} is returned. In the later
	 * case, the timeout argument is ignored and the timeout set with 
	 * {@link Socket#setSoTimeout(int)} applies for reads.<br><br>
	 *
	 * Any socket created using socket factories returned by {@link NetUtils},
	 * must use this interface instead of {@link Socket#getInputStream()}.
	 *     
	 * @see #getInputStream(Socket, long)
	 * 
	 * @param socket
	 * @return InputStream for reading from the socket.
	 * @throws IOException
	 */
	public static InputStream getInputStream(Socket socket) throws IOException {
		return getInputStream(socket, socket.getSoTimeout());
	}

	/**
	 * Returns InputStream for the socket. If the socket has an associated
	 * SocketChannel then it returns a 
	 * {@link SocketInputStream} with the given timeout. If the socket does not
	 * have a channel, {@link Socket#getInputStream()} is returned. In the later
	 * case, the timeout argument is ignored and the timeout set with 
	 * {@link Socket#setSoTimeout(int)} applies for reads.<br><br>
	 * 
	 * Any socket created using socket factories returned by {@link NetUtils},
	 * must use this interface instead of {@link Socket#getInputStream()}.
	 *     
	 * @see Socket#getChannel()
	 * 
	 * @param socket
	 * @param timeout timeout in milliseconds. This may not always apply. zero
	 *        for waiting as long as necessary.
	 * @return InputStream for reading from the socket.
	 * @throws IOException
	 */
	public static InputStream getInputStream(Socket socket, long timeout) throws IOException {
		return (socket.getChannel() == null) ? socket.getInputStream() : new SocketInputStream(socket, timeout);
	}

	/**
	 * Same as getOutputStream(socket, 0). Timeout of zero implies write will
	 * wait until data is available.<br><br>
	 * 
	 * From documentation for {@link #getOutputStream(Socket, long)} : <br>
	 * Returns OutputStream for the socket. If the socket has an associated
	 * SocketChannel then it returns a 
	 * {@link SocketOutputStream} with the given timeout. If the socket does not
	 * have a channel, {@link Socket#getOutputStream()} is returned. In the later
	 * case, the timeout argument is ignored and the write will wait until 
	 * data is available.<br><br>
	 * 
	 * Any socket created using socket factories returned by {@link NetUtils},
	 * must use this interface instead of {@link Socket#getOutputStream()}.
	 * 
	 * @see #getOutputStream(Socket, long)
	 * 
	 * @param socket
	 * @return OutputStream for writing to the socket.
	 * @throws IOException
	 */
	public static OutputStream getOutputStream(Socket socket) throws IOException {
		return getOutputStream(socket, 0);
	}

	/**
	 * Returns OutputStream for the socket. If the socket has an associated
	 * SocketChannel then it returns a 
	 * {@link SocketOutputStream} with the given timeout. If the socket does not
	 * have a channel, {@link Socket#getOutputStream()} is returned. In the later
	 * case, the timeout argument is ignored and the write will wait until 
	 * data is available.<br><br>
	 * 
	 * Any socket created using socket factories returned by {@link NetUtils},
	 * must use this interface instead of {@link Socket#getOutputStream()}.
	 * 
	 * @see Socket#getChannel()
	 * 
	 * @param socket
	 * @param timeout timeout in milliseconds. This may not always apply. zero
	 *        for waiting as long as necessary.
	 * @return OutputStream for writing to the socket.
	 * @throws IOException   
	 */
	public static OutputStream getOutputStream(Socket socket, long timeout) throws IOException {
		return (socket.getChannel() == null) ? socket.getOutputStream() : new SocketOutputStream(socket, timeout);
	}

	/**
	 * This is a drop-in replacement for 
	 * {@link Socket#connect(SocketAddress, int)}.
	 * In the case of normal sockets that don't have associated channels, this 
	 * just invokes <code>socket.connect(endpoint, timeout)</code>. If 
	 * <code>socket.getChannel()</code> returns a non-null channel,
	 * connect is implemented using Hadoop's selectors. This is done mainly
	 * to avoid Sun's connect implementation from creating thread-local 
	 * selectors, since Hadoop does not have control on when these are closed
	 * and could end up taking all the available file descriptors.
	 * 
	 * @see java.net.Socket#connect(java.net.SocketAddress, int)
	 * 
	 * @param socket
	 * @param endpoint 
	 * @param timeout - timeout in milliseconds
	 */
	public static void connect(Socket socket, SocketAddress endpoint, int timeout) throws IOException {
		if (socket == null || endpoint == null || timeout < 0) {
			throw new IllegalArgumentException("Illegal argument for connect()");
		}

		SocketChannel ch = socket.getChannel();

		if (ch == null) {
			// let the default implementation handle it.
			socket.connect(endpoint, timeout);
		} else {
			SocketIOWithTimeout.connect(ch, endpoint, timeout);
		}

		// There is a very rare case allowed by the TCP specification, such that
		// if we are trying to connect to an endpoint on the local machine,
		// and we end up choosing an ephemeral port equal to the destination port,
		// we will actually end up getting connected to ourself (ie any data we
		// send just comes right back). This is only possible if the target
		// daemon is down, so we'll treat it like connection refused.
		if (socket.getLocalPort() == socket.getPort() && socket.getLocalAddress().equals(socket.getInetAddress())) {
			LOG.info("Detected a loopback TCP socket, disconnecting it");
			socket.close();
			throw new ConnectException("Localhost targeted connection resulted in a loopback. "
					+ "No daemon is listening on the target port.");
		}
	}

	/** 
	 * Given a string representation of a host, return its ip address
	 * in textual presentation.
	 * 
	 * @param name a string representation of a host:
	 *             either a textual representation its IP address or its host name
	 * @return its IP address in the string format
	 */
	public static String normalizeHostName(String name) {
		if (Character.digit(name.charAt(0), 10) != -1) { //FIXME 
			return name;
		} else {
			try {
				InetAddress ipAddress = InetAddress.getByName(name);
				return ipAddress.getHostAddress();
			} catch (UnknownHostException e) {
				return name;
			}
		}
	}

	/** 
	 * Given a collection of string representation of hosts, return a list of
	 * corresponding IP addresses in the textual representation.
	 * 
	 * @param names a collection of string representations of hosts
	 * @return a list of corresponding IP addresses in the string format
	 * @see #normalizeHostName(String)
	 */
	public static List<String> normalizeHostNames(Collection<String> names) {
		List<String> hostNames = new ArrayList<String>(names.size());
		for (String name : names) {
			hostNames.add(normalizeHostName(name));
		}
		return hostNames;
	}

	/**
	 * Performs a sanity check on the list of hostnames/IPs to verify they at least
	 * appear to be valid.
	 * @param names - List of hostnames/IPs
	 * @throws UnknownHostException
	 */
	public static void verifyHostnames(String[] names) throws UnknownHostException {
		for (String name : names) {
			if (name == null) {
				throw new UnknownHostException("null hostname found");
			}
			// The first check supports URL formats (e.g. hdfs://, etc.). 
			// java.net.URI requires a schema, so we add a dummy one if it doesn't
			// have one already.
			URI uri = null;
			try {
				uri = new URI(name);
				if (uri.getHost() == null) {
					uri = new URI("http://" + name);
				}
			} catch (URISyntaxException e) {
				uri = null;
			}
			if (uri == null || uri.getHost() == null) {
				throw new UnknownHostException(name + " is not a valid Inet address");
			}
		}
	}

	/**
	 * Checks if {@code host} is a local host name and return {@link InetAddress}
	 * corresponding to that address.
	 * 
	 * @param host the specified host
	 * @return a valid local {@link InetAddress} or null
	 * @throws SocketException if an I/O error occurs
	 */
	public static InetAddress getLocalInetAddress(String host) throws SocketException {
		if (host == null) {
			return null;
		}
		InetAddress addr = null;
		try {
			addr = InetAddress.getByName(host);
			if (NetworkInterface.getByInetAddress(addr) == null) {
				addr = null; // Not a local address
			}
		} catch (UnknownHostException ignore) {
		}
		return addr;
	}
}
